On Wed, 24 Feb 2016, Marc MERLIN wrote: > On Wed, Feb 24, 2016 at 06:53:05AM +0000, Eric Wheeler wrote: > > Do you have the bcache stability patches? 4.3.3 might be missing some > > critical patches. > > > > Be sure to cherry-pick these from linux 4.5-rc1: > > git cherry-pick 2ef9ccbf~1..627ccd20 > > or use one of the 4.1 or 3.18 longterm kernels. > > > > I've not see any memory allocation issues before in bcache, but you > > definitely want those patches for general stability. > > I'm running 4.4.2, so I'm assuming I don't have those fixes, thanks for the > heads up. 4.1.18 has the patches, so unless there is something specific in 4.4 that you need, I recommend 4.1. We've been running 4.1.17 with patches in production for a while and it works great. Haven't tried vanilla 4.1.18 yet, but I plan to soon. > Well, your message is timely, just as you wrote this, I got bcache that > crashed my system as I was shutting down, and then I was unable to ever > reboot because bcache would detect my partitions, start bcache, and crash > before I could do anything to fix it. > > A few questions though: > 1) is there any bcache boot option I can give to disable bcache at boot > time? This is probably distribution specific. Exclude bcache from your initrd unless your rootfs is bcache (update-initramfs, dracut, etc). Maybe blacklist the module and manually modprobe it when you are ready to load it. > 2) I had to boot from rescue media and sadly the version of wipefs there > wasn't good enough to find the bcache sig and remove it. > I then tried to change the bcache cache partition type to 0, but that didn't > help either. > Eventually I had to shrink the bcache cache partition to 1 cylinder and > finally then it stopped being detected at boot and the crashes stopped. > (dd of /dev/zero would have worked, but it's an ssd, and I didn't want to > allocate blocks on the flash that had not been used yet to give more room > for garbage collection). > > Was there a better way of doing this? Probably just `make-bcache -C` of the cache with a force option? I think the superblock is in the first 2MB of the disk, so you could do something like this: dd if=/dev/zero bs=1M count=2 of=/cachedev > "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Funny, I use my mouse the same way! -Eric > Microsoft is to operating systems .... > .... what McDonalds is to gourmet cooking > Home page: http://marc.merlins.org/ > -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
